Apparatus for encoding and decoding of low-density parity-check codes, and method thereof

Abstract

An LDPC code encoding apparatus includes: a code matrix generator for generating and transmitting a parity-check matrix comprising a combination of square matrices having a unique value on each row and column thereof; an encoding means encoding block LDPC codes according to the parity-check matrix received from the code matrix generator; and a codeword selector for puncturing the encoded result of the encoding means to generate an LDPC codeword. The code matrix generator divides an information word to be encoded into block matrices having a predetermined length to generate a vector information word. The encoding means encodes the block LDPC codes using the parity-check matrix divided into the block matrices and a Tanner graph divided into smaller graphs in correspondence to the parity-check matrix.

1. An apparatus for encoding of LDPC (Low Density Parity Check) codes, which is for encoding using LDPC codes, the apparatus comprising:
 a code matrix generator for generating and transmitting a parity-check matrix comprising a combination of square matrices having a unique value on each row and column thereof; 
 an encoding means encoding block LDPC codes according to the parity-check matrix received from the code matrix generator; and 
 a codeword selector for puncturing the encoded result of the encoding means to generate an LDPC codeword. 
 
   
   
     2. The apparatus as claimed in  claim 1 , wherein the code matrix generator divides an information word to be encoded into block matrices having a predetermined length to generate a vector information word. 
   
   
     3. The apparatus as claimed in  claim 2 , wherein the block matrices comprise a combination of sub matrices having a unique value on each row and column thereof, the block matrices constituting a triangulated matrix. 
   
   
     4. The apparatus as claimed in  claim 1 , wherein the encoding means encodes the block LDPC codes using the parity-check matrix divided into the block matrices and a Tanner graph divided into smaller graphs in correspondence to the parity-check matrix. 
   
   
     5. The apparatus as claimed in  claim 1 , wherein the encoding means performs a parallel operation of the codeword in units of vector in correspondence to the parity-check matrix. 
   
   
     6. An apparatus for decoding of LDPC codes, which is for decoding LDPC codewords encoded with LDPC codes, the apparatus comprising:
 a codeword synthesizer for dividing a message comprising the LDPC codewords in a predetermined length to generate a vector message; 
 a decoding means for receiving the vector message from the codeword synthesizer and performing a parallel decoding of the codewords in units of vector message; and 
 an information restoring means for restoring the codewords decoded by the decoding means to an information word. 
 
   
   
     7. The apparatus as claimed in  claim 6 , wherein the codeword synthesizer fills a punctured portion of the LDPC codeword with a soft decision value (typically, positive infinity) corresponding to the codeword 0 to generate a vector message. 
   
   
     8. The apparatus as claimed in  claim 6 , wherein the decoding means searches for a cycle by a message-passing decoding method to generate a matrix comprising a combination of square matrices having a unique value on each row and column thereof. 
   
   
     9. The apparatus as claimed in  claim 8 , wherein the decoding means substitutes the message-passing decoding process by a cyclic shift operation to perform a parallel operation. 
   
   
     10. A method for encoding of LDPC codes, which is for encoding an information word to be encoded with LDPC codes, the method comprising:
 (a) dividing the information word to be encoded into block vectors having a predetermined length to generate a vector information word; 
 (b) generating a parity-check matrix comprising the divided block matrices; 
 (c) encoding the codeword by parallel calculation in units of vector in correspondence to the parity-check matrix; and 
 (d) puncturing the encoding result to generate a LDPC codeword. 
 
   
   
     11. The method as claimed in  claim 10 , wherein the block matrices of the step (a) comprise a combination of sub matrices having a unique value on each row and column thereof, the block matrices constituting a triangulated matrix. 
   
   
     12. The method as claimed in  claim 11 , wherein the step (b) comprises:
 configuring an overall parity-check matrix corresponding to the triangulated matrix constructed in the step (a). 
 
   
   
     13. The method as claimed in  claim 12 , wherein the overall parity-check matrix using the triangulated matrix comprises cyclic shift and binary addition. 
   
   
     14. The method as claimed in  claim 10 , wherein the step (b) comprises:
 generating a parity-check matrix having 1- or 0-valued elements from given parameters; and 
 replacing the 1-valued elements of the parity-check matrix with one selected from the sub matrices. 
 
   
   
     15. The method as claimed in  claim 10 , wherein the step (c) comprises:
 encoding the codeword using the parity-check matrix divided into the block matrices and a Tanner graph divided into smaller graphs in correspondence to the parity-check matrix. 
 
   
   
     16. The method as claimed in  claim 15 , wherein the divided Tanner graphs are constructed into regular graphs, the regular graphs being constructed into pseudo random graphs constituting each component of the overall graph. 
   
   
     17. A method for decoding of LDPC codes, which is for decoding an LDPC codeword encoded with LDPC codes, the method comprising:
 (a) dividing a message to be decoded in a predetermined length to generate a vector message; 
 (b) receiving the vector message and parallel-decoding the codeword in units of vector; and 
 (d) restoring the LDPC codeword to an information word using the parity-check matrix. 
 
   
   
     18. A method for generating a parity-check matrix of LDPC codes, which is for generating an LDPC code matrix encoded with LDPC codes, the method comprising:
 (a) searching for a cycle by a message passing decoding method to generate a matrix comprising a combination of square matrices having a unique value on each row and column thereof; 
 (b) determining 1-locations in the parity-check matrix by the cycle searching; and 
 (c) selecting one of a predetermined number of digits available for the 1-locations of the parity-check matrix, and allocating nonzero elements of the parity-check matrix.